Psychologists Jack Goncalo and Sharon Kim of Cornell University and Francis Flynn of Stanford University paired up 76 college students and asked one person to develop and pitch a concept for a movie to the other. The ideas were not stellar; one of the more creative, Goncalo says, involved a mafia family run by a young woman. But when pitched by the most narcissistic students (as evaluated by a 16-item questionnaire called the Narcissistic Personality Inventory), the ideas impressed the person evaluating the pitch roughly 50% more than did those from the least narcissistic pitchers. (The researchers judged the response to the ideas by how strongly the evaluator agreed with statements such as "it is unlikely that anyone has come up with a movie idea like this before.")

But two independent raters were not so easily wowed. Having only seen the movie pitches in written form, they found the narcissists' ideas to be about as creative as proposals from non-narcissists. The difference, the researchers say, was in the pitch itself: narcissists were more enthusiastic, witty, and charming—all traits, according to past research, that people associate with creativity.

Turns out, there's an optimal number of narcissists to add: two. It seems like two narcissists tend to feed off each other and become even more creative. However, if you add more, then the team tends to devolve into ego fights.